Mobile network will be utilized world wide in the 21st century. With recent ten years of development, wireless techniques have changed people's wired experience of more than one hundred years. In this situation, Fixed and Mobile Convergence (FMC) has become an inevitable way for the operators of fixed networks.
At present, in the industry, much beneficial research has been made on the FMC in the planes of service, core network, terminal, etc. FIG. 1 shows schematic diagrams illustrating structures of an FMC network model based on core network and an FMC network model based on access network, in which FIG. 1(a) is a schematic diagram illustrating the structure of an FMC network model based on core network. However, little research has been made on the FMC in the plane of access network in the industry.
As is well known, the mobile network is mainly based on connection-oriented tunnel techniques. At present, there are two major trends for the mobile network, i.e., the third generation communication (3G) network and World Interoperability for Microwave Access (WiMAX) network. The 3G network has the characteristics of walled garden, private mobile mechanism, high-layered tunnel and large overhead. The conflict is prominent especially for voice services which are usually in short packets. The WiMAX network has the characteristics of opened network, utilization of mobile IP technique and a relative flat protocol stack. However, how to support mobile Virtual private network (VPN) is a difficulty in the mobile network, and also the future trend of the mobile network.
Ethernet technology has been developed for over 30 years up to now. Statistically, up to 97% of terminal users perform data transmission and various networking via Ethernet interfaces.
The emergence of Provider Backbone Transport (PBT) technique not only fills up the gap between local area network and wide area network so as to become one of the hottest industry topics of telecommunication-level metropolitan area Ethernet, but also draws serious attention of Digital Subscriber Line (DSL) Forum. The PBT technique is expected to become the primary transport technique of next generation wired access network.
The object of IEEE 802.1ah is to define a new architecture and bridge protocol interoperable and compatible with the Provider Bridge (PB) of 802.1ad (also referred to as 202.1q in 802.1q (QinQ)), so as to connect a plurality of PB networks together, to reach up to at least 224 service virtual local area networks.
FIG. 2 shows the structure of a provider backbone bridge network defined in 802.1 ah. The network as shown in FIG. 2 is constructed based on 802.1 ad, and may package a PB message in a Provider Backbone Bridge (PBB) message, so as to provide a layered network and to provide a basis for Ethernet connection or Ethernet tunnel technique.
Table 1 shows the package of 802.1ah.
TABLE 1B-DAB-SAB-TagI-TagS-TagC-DAC-SAC-DATA
As shown in Table 1, B-DA is provider backbone bridge destination Media Access Control (MAC) address; B-SA is provider backbone bridge source MAC address; B-Tag is provider backbone bridge tag; I-Tag is service instance tag; S-Tag is service tag; C-DA is customer destination MAC address; C-SA is customer source MAC address; and C-DATA is customer data.
As shown in Table 1, the customer message to be transferred from PB to PBB network is completely packaged in the PBB message. The provider backbone bridge MAC addresses (B-MAC) (i.e., B-DA and B-SA) are the addresses of PBB devices. B-Tag is defined according to 802.1Q standard. In the PBB network, a message may be forwarded in a standard Ethernet manner according to only B-MAC and B-Tag.
In addition, as can be known from Table 1, in the layered network as shown in FIG. 2, the MAC address of customer is isolated from that of the provider network equipment. The tag of customer data is also separated from that of the provider.
The original intention and merits of PBT lies in that PBT deftly changes the connectionless Ethernet into a connection-oriented tunnel technique, by excavating the conventional Ethernet techniques and the related equipment, based on IEEE 802.1ah standard specifications. Whether the PBT, with opened protocols and flat-layered tunnel, is also suitable to the wireless access network is an important issue to be solved by the FMC of access network. The PBT technique has the following characteristics
1. The device implementing PBT is required to support individual Virtual Local Area Network (VLAN) learning (IVL)
2. Because of its support for IVL, the device implementing PBT may be classified into PBT VLAN, i.e., connection-oriented VLAN, and connectionless VLAN, i.e., ordinary VLAN. In other words, a part of PBT-related devices may be designated as PBT VLAN, separated from other ordinary VLAN so that the PBT VLAN and the ordinary VLAN will not interfere with each other
3. MAC address learning and spanning tree protocol is closed in PBT VLAN
4. The functions of multicast and broadcast are closed in PBT VLAN.
FIG. 3 shows an schematic diagram illustrating the structure of a PBT transport network, in which a provisioning and management functional system is connected with all of the Provider Edge Bridges (PEs) and Provider Bridges (Ps), and is adapted for configuration and link maintenance, such as the control and management functions including state detection, path protection, etc.
The PBT transport network as shown in FIG. 3 contains a series of PEs and Ps which are generally Ethernet exchanges supporting IVL. These PEs and Ps are respectively configured with destination device MAC addresses and PBT Virtual local area network identifications (VIDs), and form the destination device MAC addresses and the PBT VIDs into tags, i.e., identifications of paths, and forward the tags over a series of Ethernet exchanges supporting IVL. In this way, an Ethernet Switched Path (ESP) is formed. The ESP may be considered as a connection, i.e., Ethernet Virtual Connection (EVC) or tunnel. The MAC address, VID and the forwarding manner thereof in the PBT technique are consistent with those in IEEE 802.1q standard.
The process that the PBT transport network as shown in FIG. 3 forwards data is as follows.
First, the provisioning and management functional system configures the PBT links, for example, configures the PBT links dynamically or statically via the control plane of Generalized Multi-Protocol Label Switching (GMPLS), and maintains the states of the PBT links.
Then, the provisioning and management functional system learns the MAC addresses by using IVL on the network nodes through which the Ethernet switching path over the PBT transport path passes, for example, on PEs and Ps as shown in FIG. 2, and configures a MAC address forwarding table of PBT.
Thus, a PE may forward the customer data sent from a customer network to PE to a next hop network node according to the forwarding table configured as above. The next hop network node then forwards the customer data to another next hop network node according to the forwarding table configured as above, until the customer data reaches a PE connected to the destination customer network. The intermediate node(s) only forward the message and do not perform other processing to the message.
The above described PBT and IEEE 802.1 ah techniques have been further applied to access network. Nevertheless, either of them supports the terminal mobility in MAC layer.
A Mobile IP (MIP) standard of IETF in the prior art is based on IP (Internet Protocol) protocol. The MIP standard has the following disadvantages.
1. The MIP standard is a non-connection-oriented mobile IP technique based on route, and can not provide a Quality of Service (QoS) guarantee, accordingly is not suitable for multimedia communication yet.
2. The MIP standard does not support layer two mobile VPN and E2E VLAN.
3. In the case that the utilization of IPv4 and IPv6 terminals are mixed, the network must support both stacks of IPv4 and IPv6, resulting in a relative complicated network. Thus, the IPv4 network can not be reconstructed into an IPv6 network smoothly.
4. There is a limitation of an IP hop between a mobile node (MN) and a foreign agent.
5. When moving in a high speed, a mobile node is faced with the problems such as frequent handover and registration and update of foreign agent (FA). The MIP interaction information, such as registration in IP layer, etc., occupies much radio bandwidth, and the registration interaction information in IP layer may result in a relative large handover delay. This can not meet the requirements of high speed handover.